Playback apparatus for audiovisual disc records

ABSTRACT

In a playback apparatus a first sync code is detected from a series of data blocks to separate binary digits of multi-channel still-picture data from binary digits of multi-channel audio and computer-control data. Second and third sync codes are subsequently detected from the separated binary digits of the audio and computer-control data. A data selector is responsive to a channel selection manual command signal and to the second sync code for selecting the audio data words of a desired channel and the computer-control data bits of a desired channel from the separated binary digits of the multi-channel audio and computer-control data. A video converter is responsive to the command signal for storing the still-picture data words of a desired channel for a predetermined period and converting the stored data words into an analog video signal for application to a visual display. An audio converter converts the selected audio data words into an analog audio signal for application to a loudspeaker. A decoder is provided to respond to the detected third sync code by decoding the computer-control binary digits of the selected channel into computer-control data words for application to a personal computer which is coupled to the display.

RELATED APPLICATION

The present invention is related to our Copending U.S. patentapplications Ser. No. 609,193 filed May 11, 1984, titled "RotaryRecording Medium", invented by H. Sugiyama et al. and Ser. No. 609,237filed May 11, 1984, titled "Rotary Recording Medium ReproducingApparatus", invented by H. Sugiyama et al, both applications beingassigned to the same assignee as the present application.

BACKGROUND OF THE INVENTION

The present invention relates to a playback apparatus for disc records,and more particularly to a playback apparatus for audiovisual discrecords in which a series of still-picture digital video data and audiodigital data is recorded in tracks.

The recent introduction of video discs and digital audio discs and theincreasing use of personal computers have created a demand foraudiovisual systems that combine the audio and visual features with theversatile capabilities of computers.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a playback apparatusfor disc records which store audiovisual information.

The playback apparatus of the invention is adapted to reproduce discrecords of the type in which information is recorded as microscopic pitsin radially spaced apart track turns, the information being a sequenceof data blocks of multiplexed data words of multi-channel still-picturevideo signals, data words of multi-channel audio signals and data bitsof multi-channel computer-control signals, the audio data words and thecomputer-control data bits being organized into a sequence ofsub-blocks, the volume of information contained in the computer-controldata bits of each of the sub-blocks being much smaller than the volumeof information contained in the audio data words of each of thesub-blocks, the information further including a first sync code foridentifying each data block, a second sync code identifying eachsub-block and a third sync code identifying a sequence of thesub-blocks.

The apparatus comprises means for detecting the recorded informationfrom the disc record to recover the sequence of data blocks. The firstsync code is detected from the recovered data blocks to separate binarydigits of still-picture data of each channel from binary digits of theaudio and computer-control data of each channel, and the second andthird sync codes are subsequently detected from the separated binarydigits of the audio and computer-control data. A data selector isresponsive to a channel selection signal supplied from a keyboard and tothe detected second sync code for selecting the audio data words of adesired channel and the computer-control data bits of a desired channelfrom the separated binary digits of the audio and computer-control dataof said channels. A video converting means, or decoder is responsive tothe selection signal for storing the still-picture data words of adesired channel for a predetermined period and converting the storeddata words into an analog video signal for application to a visualdisplay. An audio converter converts the selected audio data words intoan analog audio signal for application to a loudspeaker. A decoder isprovided to respond to the detected third sync code by decoding thecomputer-control binary digits of the selected channel intocomputer-control data words for application to a personal computer whichis coupled to the display.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in further detail with referenceto the accompanying drawings, in which:

FIG. 1 is a block diagram of an audio section of the recording apparatusof the invention;

FIG. 2 is a timing diagram showing the relationship between clockpulses, format and field sync codes;

FIG. 3 is an illustration of a data structure by which audio data andcomputer-control data are organized into a series of blocks;

FIG. 4 is a block diagram of a video section of the recording apparatusin which audio and video signals are combined and recorded;

FIG. 5 is an illustration of a data structure of the still-picture videoinformation;

FIG. 6 is an illustration of a data structure of a time-divisionmultiplexed signal;

FIG. 7 is an illustration of a format by which address bits stored ineach data block of FIG. 6 are organized;

FIG. 8 is an illustration of a disc record;

FIG. 9 is a block diagram of a playback apparatus according to thepresent invention;

FIG. 10 is a timing diagram illustrating the relationship between fieldsync codes and computer-control data for NTSC compatible systems; and

FIG. 11, consisting a-e, is a timing diagram illustrating therelationship between field sync codes and computer-control data forPAL/SECAM compatible systems.

DETAILED DESCRIPTION

Referring now to FIG. 1, there is schematically shown an audio sectionof a recording apparatus according to the present invention. An audioprogram recorder 10 contains sixteen-channel program sources of audioinformation such as narrations and sound effects to be presentedsimultaneously with a corresponding prerecorded still-picture program.The volume of information contained in each still-picture program ismuch smaller than the volume of information contained in the normal(moving-picture) video program. As long as the amount of informationpermits, the still-picture data may contain an animated picture which isto be displayed in a window within the field of a still picture. Eachaudio program is a digital record of 44.1-kHz samples of 16-bit word ofaudio-band signals on magnetic tape using current digital techniques forhigh quality music recordings. The narration programs are provided intwo language versions. Although sound effects of corresponding programsmay be independent of languages, the sixteen audio program sources aredivided into two language versions of 8 channels each to permit users toselect a desired language program. The digital audio programs of eachlanguage version are reduced to 8-bit word by data compressors 11a andllb. and 11b.

Clock pulses at a frequency of 44.1 kHz are generated by a clock source31 and supplied to address generators 13a, 13b, 23a, 23b, 15, 25 tosequentially increment their address counts.

Eight-bit digital audio data fed to a first buffer RAM 12a aresequentially stored in specified locations in response to address codesprovided by an address generator 13a. Likewise, data fed to a secondbuffer RAM 12b are sequentially stored in specified locations inresponse to address codes from address generator 13b.

A computer-control data recorder 20 contains sixteen-channel prerecordedcomputer-control data sources such as graphic symbols and characters tobe superimposed on the still picture and musical notes to be fed to apersonal computer for automatic music play. The computer-control datasources are likewise divided into two language versions of 8 channelseach corresponding to the audio program recorder 10.

Digital control data outputs on No. 1 to No. 8 channels of the firstlanguage version are applied from recorder 20 respectively to parity-CRC(cyclic redundancy check) code generators 21a and fed to a third bufferRAM 22a of a data formatting circuit 30 and sequentially stored inlocations by an address generator 23a. Control data outputs on No. 9 toNo. 16 channels of the second language version are applied respectivelyto parity-CRC (cyclic redundancy check) code generators 21b and fed to afourth buffer RAM 22b and sequentially stored in locations by an addressgenerator 23b.

The output terminals of the first and second buffer RAMs 12a and 12b areconnected to first and second formatting RAMs 14 and 24, respectively,and the output terminals of the third and fourth buffer RAMs 22a and 22bare connected respectively to the first and second formatting RAMs 14,24. Digital data stored in buffer RAMs 12a, 12b, 22a, 22b are recalledby address generators 13a, 13b, 23a, 23b and transferred to formattingRAMs 14, 24 in response to address generators 15 and 25.

The 44.1-kHz clock pulse is also supplied to a format sync generator 32.This sync generator generates, at every count of five clock pulses, an8-bit format sync code composed of "11111111" at a rate corresponding tothe horizontal sync of a video format. The clock is also applied to a"field" sync code generator 33, which generates a field sync code"10000000" at every count of five clock pulses and generates a burst ofthree such field sync codes for a duration of 15 clock intervals aseries of "00000000" bits during the remainder of each field interval.For application to the NTSC systems, field sync generator 33 counts 736clock pulses to generate a burst of field sync codes. In PAL or SECAMsystem applications, field sync generator 33 counts every 881 clockpulses to generate a field sync. The format and field sync codes areapplied to formatting RAMs 14 and 24 to be organized in a data structureto be described hereinbelow.

A memory control circuit 34 derives timing signals from clock pulses andcontrols address generators 13a, 13b, 23a, 23b, 14 and 24 at appropriatetimes to organize the audio and control program data with format andfield sync codes. The operation of the memory circuit 34 will bevisuallized with reference to FIGS. 2 and 3.

As shown in FIG. 2, format sync generator 32 generates a format synccode ("11111111") at each count of five clock pulses, while field syncgenerator 33 generates a series of three field sync codes ("10000000")for each field interval in which a total of 736 clock pulses,exist forNTSC applications. In respohse to a format sync code, memory controlcircuit 34 enables address generator 15 to store the eight bits of theformat sync code respectively into the cell locations of formatting RAM14 corresponding to the first to eigth rows on the first column. Addressgenerator 25 is also enabled to address the first through eigth rows ofthe first column of formatting RAM 24 to store the field sync code bits"10000000". At the same time, memory control unit 34 enables addressgenerators 23a and 23b to read control program data bits Pl through P8from buffer RAM 22a into cell locations of formatting RAM 14 in theninth through sixteenth rows of the first column and read controlprogram data bits P9 through P16 from the buffer RAM 22b into celllocations of memory 24 in the ninth through the sixteenth rows of thefirst column.

In response to a subsequent clock pulse memory control unit 34 enablesaddress generators 13a and 13b to read audio program data words CH1-1and CH2-1 on channels No.1 and No. 2 from buffer RAM 12a into the celllocations of RAM 14 corresponding to the first to sixteenth rows on thesecond column and read audio program data words CH-9 and CH10-1 onchannels No. 9 and No. 10 from buffer RAM 12b into the cell locations ofRAM 24 corresponding to the first to sixteenth rows of the secondcolumn.

In a similar manner, audio program data words CH3-1 and CH4-1 onchannels No. 3 and 4 are stored in the third column of the formattingRAM 14 and data words CH11-1 and CH12-1 on channels No. 11 and 12 arestored in the third column of the formatting RAM 24. Audio program datawords CH5-1 and CH6-1 on channels No. 5 and 6 are stored in the fourthcolumn of the formatting RAM 14 and data words CH13-1 and CH14-1 onchannels No. 13 and 14 are stored in the fourth column of the formattingRAM 24. Audio program data words CH7-1 and CH8-1 on channels No. 7 and 8are stored in the fifth column of the formatting RAM 14 and data wordsCH15-1 and CH16-1 on channels No. 15 and 16 are stored in the fifthcolumn of the formatting RAM 24. At the count of first 5 (five) clockpulses at the beginning of each field interval, the sixteen audioprogram data words and the sixteen control data bits are organized intoa No. 1 "audio" block together with the format and field sync codes.

Subsequent audio blocks No. 2 to No. 3 are organized in response to theoccurrence of each format sync code in a manner identical manner to thatjust described, so that the field sync code "10000000" is stored in eachof these blocks. In blocks that follow the No. 3 block, the celllocations of memory 24 specified for field sync codes are filled with"00000000" bits. In NTSC applications, the field sync exists for15-clock interval and "00000000" bits are stored in audio blocks during720-clock interval. Control data bits will be decoded during playbackinto control words for a period of 600-clock interval which existsduring said 720-clock interval.

Immediately after the formation of each audio block, all data stored inRAM 14 are sequentially sent on 16-line common bus 16 to aparallel-to-series converter 35 and all all data stored in RAM 24 aresequentially sent on 16-line common bus 26 to the converter 35. Thisparallel-to-series converter can be implemented as part of aconventional video processor available as DS-900 which rearranges theserial data bits into a video format suitable for conventional videotape recorders. The serially converted data bits are applied to a videotape recorder 36, FIG. 4.

In FIG. 4, an 8-channel still-picture program recorder 40 contains eightchannels of still picture program. These still-picture programs aretime-division multiplexed so that "field" components of the individualprograms occur at 19.2-second intervals.

Each still-picture video program is prepared by initially sampling theluminance component of a video signal at 9 MHz and quantizing thesamples into 8-bit codes and sampling the color difference components(R-Y, B-Y) at 2.25 MHz and quantizing the color difference samples into8-bit codes. These digitized luminance and color difference signals arethen converted to a digital record of 88.2-kHz luminance andcolor-difference samples of 8-bit wordlength. For convenience, two pixeldata bits are combined to form a 16-bit word. FIG. 5 illustrates a datastructure of each still-picture program. One complete "field" of stillpicture reproduction is organized by 114 successive still-picture datablocks each composed of luminance components Y.sub.(1+4i)j,Y.sub.(2+4i)j, Y.sub.(3+4i)j and Y.sub.(4+4i)j, and color-differencecomponents (R-Y)_(j) and (B-Y)_(j), where i represents an integerranging from zero to 114 and j represents an integer ranging from unityto 114.

Each still-picture component Y is composed of a group of 143 wordsrepresenting the luminance values of a vertical array of 286 pixelsarranged on the jth column of the still picture. Color-differencecomponents (R-Y) and (B-Y) are each composed of 143 words representingthe color difference values of pixels arranged on the jth column fromthe left of the still picture. A complete still picture comprises atotal of 101,964 words.

Each of the luminance and color-difference components is preceded by a6-word header which permits playback system to identify the videocomponent that follows. In more detail, 15 higher significant bits ofthe first word of the header comprise a sync code and the leastsignificant bit of the first word and the whole bits of the second wordcomprise a mode identification code. The third word of the headercomprises a 16-bit address code indicating the memory locations of a525-line system into which the first 8 bits of the following 143-wordstill picture information are to be stored, the fourth word of theheader comprising a 16-bit address code indicating the memory locationsof a 625-line system into which the first 8 bits of the following143-word still picture information are to be stored. The fifth and sixthwords of the header are all set to zero bits for future use.

The No. 1 to No. 8 still-picture programs which are respectivelyassociated with No. 1 (No. 9) to No. 8 (No. 16) audio program sources,are fed to parallel-to-series converter 41 similar in operation toconverter 35 and thence to a video tape recorder 42.

Video tape recorders 35 and 42 are synchronized with each other inresponse to a 44.1-kHz, 8-bit sync generator 36 to play back therecorded material in synchronism and apply the recorded signals to atime-division multiplexer 37. The audio and still-picture video databits are time-division multiplxed into a series of combined data blocksshown in FIG. 6. Each data block of the time-division multiplexed signalbegins with an 8-bit sync code supplied from the clock-rate syncgenerator 36, followed by a 16-bit word of audio program derived fromformatting RAM 14 assigned to a first time slot TS-1 and a 16-bit wordof audio program derived from formatting RAM 24 assigned to a secondtime slot TS-2. To the third and fourth time slots TS-3, TS-4 of theblock are assigned two data words of each of the 16-bit still-pictureprograms. Sixteen-bit words of P- and Q-parity codes are derived fromthe data bits on time slots TS-1 to TS-4 by a parity bit generator 38and assigned to the fifth and sixth time slots TS-5 and TS-6. A CRC code(cyclic redundant check code) of 23-bit wordlength are derived from thedata and parity bits on time slots TS-1 to TS-6 by a CRCC generator 39and assigned to the seventh time slot TS-7. The CRC code is followed byan address bit ADR and a user's bit U, completing a block with a totalof 130 bits. The 8-bit sync words are generated at a repetition rate of44.1 kHz, so that each data block is organized in the period of 22.6microseconds.

Since NTSC-system video discs are currently turned at a speed of 889.1(=59.94×60/4) RPM, compatibility with the NTSC system can be ensured byrecording a total of 2940 (=44056×4/59.94) data blocks of FIG. 6, whichis equivalent to four data fields, on each track turn. In that instancethe 196-bit address data can be recorded in fifteen different locationson each track turn. As shown in FIG. 10, during a 720-clock period whichruns from the 16th to 736th clock pulse, control data bits exist for600-clock period which runs from the 61st to 661th clock pulse.

On the other hand, PAL and SECAM system video discs are currently turnedat a speed of 750 (=50×60/4) RPM. Compatibility with the PAL and SECAMsystems is ensured by recording a total of 3528 (=44100×4/50) datablocks can be on each track turn, with the 196-bit address data beingrecorded at 18 different locations on each track turn. While three fieldsync codes can be uniformly generated at each field interval for theNTSC compatible system, this technique cannot simply apply to thePAL/SECAM compatible system. As shown in FIG. 11, during each of threefull turns of disc for every five full turns, three field sync codes("10000000") are generated in sequence for fifteen clock intervals ateach of the first, second and third quarter turns and five field synccodes ("10000000") are generated in sequence during twenty-five clockperiod at the fourth quarter turn. During each of two full turns of discfor every five full turns, three field sync codes are generated inseries at each of the first, second and third quarter turns and fourfield sync codes are generated in sequence for twenty clock intervals atthe fourth quarter turn. In this way, the interval between successivefield sync signals can uniformly be spaced at 865-clock intervals.

To establish proper timing for initiating decoding operation on thecontrol data bits, the latter is stored in the No. 13. to No. 133 audioblocks which exist during the period between the 61th to 661st clockpulses of each field interval. Thus, the cell locations Pl to P16 ofRAMs 14 and 24 are filled with binary 0's during the period in which thecontrol data bits do not exist.

During playback each address bit will be combined with address bits ofother data blocks to form 196-bit address data composed of four 49-bitaddress blocks, one of which is shown in FIG. 7. The 49-bit addressblock begins with a 24-bit word of address sync whose code formatdiffers from other address sync depending on the address code thatfollows. A 4-bit word of mode selection code follows the address sync,first two bits of the mode selection code indicating program sources andsecond two bits indicating normal/stop mode identification. A 20-bitaddress code and a single-bit parity follow in succession. The addresscode indicates the amount of time elapsed from the start of recordedmaterial or the identification number of the program being reproduced.

The time-division multiplexed signal is supplied to a scrambler 43 whereit is mixed with a pseudo-random bit sequence or maximum length seriesthrough an Exclusive 0R gate. The scrambled data bits are fed via aswitch 51 to a video disc recording apparatus 52 of a known constructionwhere the signal is frequency modulated using modified frequencymodulation (MFM) technique to make the output data stream contain asufficient amount of clock information, and recorded on the surface of amaster disc 53 mounted a turntable 54 such that four successive fieldsof video information are recorded on each track turn. A normal videoprogram is supplied from a conventional video program source 50 to therecording apparatus 52 where it is frequency modulated as in the outputof multiplexer 37. The switch 51 is initially positioned to the right torecord the normal video progran on an outer area of the disc 53 asmarked by parallel-hatching in FIG. 8 and the switch 51 is then moved tothe left to record the output of multiplexer in the inner area of thedisc as marked by cross-hatching to produce a hybrid of video and audioprograms on a single disc record. The frequency modulated signalproduces a series of microscopic pits on the surface of the master discalong radially spaced apart grooveless track turns. In practicalembodiment, tracking control signals are recorded as microscopic pitsalong each side of the track in a manner known in the art.

FIG. 9 is an illustration of a playback apparatus according to thepresent invention. A capacitance detector circuit 60 detects capacitivevariations on a disc record which is mass-produced from the master discand feeds its output to a frequency demodulator 61. The normal (movingpicture) video signal is decoded by a normal video playback section 62of known circuitry and fed to a CRT display 63. The audio/still-picturesignal is descrambled by a descrambler 64 in a manner inverse to that ofthe scrambler 43. The 8-bit sync code contained in the scrambled TDMsignal is detected by a clock-rate sync detector 65 which generaterectangular pulses at one-half the clock rate. To establish propertiming, the output of sync detector 65 is applied to descrambler 64,data selector 66 and controller 73.

The descrambled data bits are applied to an error detector 67 and anerror corrector 68. Using the CRC code contained in the descrambledoutput, error detector 67 decodes the data bits to detect a word inerror and provides an instruction to corrector 68 to rectify the error.The audio data bits on time slots TS-1 and TS-2 are applied in serialform to a series-to-parallel converter 69, while the still-picture databits on time slots TS-3 and TS-4 are applied to a still-picture decoder70 of known circuitry a thence to the CRT display 63. Theseries-to-parallel converter 69 provides conversison of the serial datainto a form identical to the two-dimensional format of FIG. 3 andapplies the data in parallel form to data selector 66. The audio databits are further applied to a format sync detector 71 to detect formatsync codes.

Program selection command is entered to a keyboard 72 of a personalcomputer 74. A controller 73 decodes the channel selection command fromkeyboard 72 and counts the output of sync detector 65 in response to thedetection of a format sync code by detector 71 and generates a channelselection code. The channel selection code is applied to data selector66 and still-picture decoder 70. Controller 73 further provides a fieldsync extraction signal to data selector 66 to allow it to pass fieldsync bits to a field sync detector 76. Still-picture decoder 70 includesa memory in which the selected still picture program is retained for aperiod of 19.2 seconds so that the selected audio and control programsare presented simultaneously with the retained picture.

The audio program of the desired channel appears at terminals 81 whichcorrespond to all the rows of the format of FIG. 3 and the controlprogram of that desired channel appears at terminals 82 which correspondto the 9th to 16th of RAMs 14 and 24. Audio decoder 78 translates the8-bit audio digital signal into analog form and applies it throughamplifier 79 to a loudspeaker 80.

Field sync detector 76 essentially comprises a low-pass filter whichintegrates the successively arrived binary 1's of the field sync and acomparator which compares the integrated value with a preset value. Thecomparator generates an output when the detector 76 receives three fieldsync bits in succession. The output of field sync detector 76 switchesfrom low to high levels in response to the arrival of a valid fieldsync. Decoder 77 includes an error detection and correction circuitwhich utilizes the parity and CRC codes inserted by parity/CRCCgenerators 21a, 21b to detect and correct words in error.

On the other hand, in a PAL/SECAM compatible system, the output of fieldsync detector 76 remains at high level for a period of 865 clockintervals to permit decoder 77 to decode the control data bits whichexist during 600-clock period.

The control data words decoded by decoder 77 are applied to personalcomputer 74. If the control program is graphic or character data, thecomputer 74 superimposes graphic symbols or characters on the stillpicture being displayed, and if the control program is musical notes,the computer controls a musical instrument, not shown, to play music.

What is claimed is:
 1. A playback apparatus for disc records in whichinformation is recorded as microscopic pits in radially spaced aparttrack turns, said information being a sequence of data blocks ofmultiplexed data words of multi-channel still-picture video signals,data words of multi-channel audio signals and data bits of multi-channelcomputer-control signals, said audio data words and saidcomputer-control data bits being organized into a sequence ofsub-blocks, the volume of information contained in said computer-controldata bits of each of said sub-blocks being much smaller than the volumeof information contained in said audio data words of each of saidsub-blocks, said information further including a first sync code foridentifying each data block, a second sync code identifying eachsub-block and a third sync code identifying a sequence of saidsub-blocks, the apparatus comprising:means for detecting said recordedinformation from said disc record to recover said sequence of datablocks; means for detecting the first sync code from the recovered datablocks and separating binary digits of still-picture data of eachchannel from binary digits of the audio and computer-control data ofeach channel; manual command entry means for generating a channelselection signal in response to a manual command; means for detectingthe second and third sync codes from the separated binary digits of theaudio and computer-control data; data selecting means responsive to thechannel selection signal and the detected second sync code for selectingthe audio data words of a desired channel and the computer-control databits of a desired channel from the separated binary digits of the audioand computer-control data of said channels; video converting meansresponsive to the selection signal for storing the still-picture datawords of a desired channel for a predetermined period and converting thestored data words into an analog video signal for application to avisual display means; audio converting means for converting the selectedaudio data words into an analog audio signal for application to anelectroacoustic means; and decoding means responsive to the detectedthird sync code for decoding the computer-control binary digits of theselected channel into computer-control data words for application to apersonal computer which is coupled to the display means.
 2. A playbackapparatus as claimed in claim 1, wherein said disc record includes astorage area in which an analog video signal is recorded, furthercomprising means for reproducing the recorded analog video signal forapplication to said visual display means.
 3. A playback apparatus asclaimed in claim 1, wherein said information is frequency modulatedprior to being recorded in said record, further comprising means forfrequency demodulating said recovered data blocks.
 4. A playbackapparatus as claimed in claim 1, wherein said recorded informationfurther includes an error detection code and an error correction codederived from binary digits contained in the data block and appended toeach data block, further comprising means responsive to said errordetection and correction codes for detecting errors in data words ofeach data block and correcting the errors.